الفهرس 
Pulp and paper manufacturing processesOnly 14 pages are availabe for public view
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Abstract
Wood is the main fibrous raw material used for pulp and paper production, since Egypt lacks forest; bagasse and rice straw represent the main fibrous source for pulp and paper production. These raw materials are inferior to soft wood in several aspects with regard fibre length and properties of paper sheet as well as pulping process for paper production. A considerable amount of other substances, such as organic (CPAM, CMFC, Ch, and CS) or inorganic (bentonite, GCC) are added to pulp prior to sheet formation. The main objective of this thesis is to study different kinds of synthetic or natural polymers and indigenous clay (bentonite) as a drainage and retention aids in paper production from different kinds of pulps. The drainage, retention and drying stages are important factors, to optimize the process of sheet formation. Various chemical additives are added to the fibre suspension usually synthetic polymers such as cationic polyacrylamide CPAM or natural polymers such as cationic starch CS, chitosan Ch, cationic chitosan C-Ch and cationic microfibrillated cellulose C-MFC to improve the economics of these stages. Their function is to act as retention aids and/or dewatering aids. Other inorganic microparticles, such as bentonite are added to improve the quality of final paper sheet to avoid loss of fiber fines and fillers and to optimize these processes. Bentonite is a clay mineral which is smectite clay in addition to montmorillonite. The unique properties of bentonite are hydration, swelling and water absorption which makes it a valuable material for a wide range of applications especially in papermaking. In this study, three bentonite types were used: bentonite paper grade Bt-PG, bentonite ICMI Bt-ICMI and commercial one under trade name hydrocol OC Bt-OC. They were characterized by XRD, SEM, particle size distribution and their electrical behaviour by zeta potential. It was found that Bt-PG contains the highest montmorillonite content 59.22%, have the smallest diameter 123 nm with high distribution percent, and zeta potential - 9.5 mV in tap water. Also Bt-ICMI contains 5.7% montmorillonite and 5% Iron content, diameter of 154 nm with high distribution percent and zeta potential of - 12.2 mV. Bt-OC contains 6.7% montmorillonite and 6% Iron content, diameter of 123 nm with high distribution percent and zeta potential of - 11.7 mV. Four kinds of pulp were used in this study, softwood SW, a bleached kraft pulp mainly from pine fibers, hardwood HW, 100% Eucalyptus, bagasse pulp BP from Quena company, a bleached kraft pulp and rice straw RS from RAKTA company, a bleached soda pulp. The pulps were characterized regarding their chemical composition, morphological characteristics (MORFI analysis), water retention value WRV, and their electrical charge. SW has long fiber; HW and BP have almost similar chemical and MORFI characters and have different charges due to the type of pulping and bleaching methods used. RS has high fine and silica contents. Five organic flocculants were used in this study; three of them were commercially available (CPAM, CS and Ch). The other two (C-MFC and C-Ch) were prepared in the lab; The MFC was prepared from kraft bleached bagasse pulp by using a two-chamber high-pressure homogenizer. Cationic MFC was prepared by using β- chloroethylamine and the resultant was refluxed with methyl iodide. The cationic chitosan was prepared by reaction of chitosan with 2,3- epoxypropyltrimethyl ammonium chloride. They were characterized by FT-IR and by their N-content (0.5% for C-MFC and 6.9% for C-Ch). All flocculants were characterized regarding their cationic demand by using colloidal titration. CPAM was found to be the best flocculants due to its high positive charge density 1330 μeq/g. Ch was dissolved in acetic acid before being used which gives it the cationic demand 1180 μeq/g, while cationic demand of CS, C-MFC and CCh were 500, 280 and 250 μeq/g respectively. The organic flocculants and/or bentonite were tested as drainage aids for all pulps. All flocculants were added from 0.5 to 10 mg/g pulp. The optimum dose that gives the best improvement in drainage was 1 mg flocculant/g pulp for all pulps except for RS (5 mg CPAM/g and 2 mg Ch/g) where RS contains high fine and silica contents. Thus a large amount of polymer must be used before there was any significant increase in drainage. This is probably because of the high concentration of dissolved anionic cellulosic fines and hemicelluloses in furnishes containing rice straw pulp and because of the comparatively high electrostatic charges on fibers of rice straw pulp. For SW, in case of using flocculants, CPAM was the best flocculants that gave the best improvement in drainage 11%. In case of using different bentonite in combination with flocculants, the best improvement in drainage was obtained on using Ch with all kinds of bentonites; the highest decrease was 59% and was obtained in case of using Ch with Bt-PG. For HW, in case of using flocculants, CPAM was the best flocculants that gives the best improvement in drainage 14%. In case of using different bentonite in combination with flocculants, the best improvement in drainage was 56% and was obtained in case of using CPAM with Bt-ICMI. For BP, in case of using flocculants, CPAM was the best flocculants that gives the best improvement in drainage 28%. In case of using different bentonite in combination with flocculants, the best improvement in drainage was 67% and was obtained in case of using CPAM with Bt-PG. For RS, in case of using flocculants, CPAM was the best flocculants that gives the best improvement in drainage 23%. In case of using different bentonite in combination with flocculants, the best improvement in drainage was 68% and was obtained in case of using CPAM with Bt-PG. As shown above the highest percent decrease in drainage was obtained with RS and BP in case of using CPAM with Bt-PG. This is attributed to CPAM has high charge density and Bt-PG has high montmorillonite content and the smallest diameter for particles of Bt-PG compared to other bentonite samples. Thus the decrease in drainage time was dependent on morphological structure of pulp, charge density of flocculants and bentonite structure. The fillers are incorporated into the paper sheet to improve paper properties. The retention of fillers in the sheet requires retention aids. This trend has resulted in dual and multi-component retention aid systems, one of which is the combination of flocculants and microparticles (bentonite). The optimum dose for flocculants (1 mg/g pulp) and bentonite (10 mg/g pulp) that obtained in the drainage results were used to study the effect of their addition on retention of GCC filler in paper making. The results showed that percent of GCC retained in sheets was very low without using of either flocculants or Bt. The percent of GCC retained was 1.1% for SW, 7.8% for HW, 7.7% for BP and 0.8% for RS. For SW, in case of using flocculants, the highest percentage of GCC retained was 66% which obtained with CPAM. Also in case of using different bentonite in combination with flocculants, the highest percentage of GCC retained was 95% which obtained in case of using CPAM with Bt-ICMI. For HW, in case of using flocculants, that the highest percentage of GCC retained was 79% which obtained with CPAM. Also in case of using different bentonite in combination with flocculants, the highest percentage of GCC retained was 96% which obtained in case of using CPAM with Bt-PG and Bt-OC. For BP, in case of using flocculants, the highest percentage of GCC retained was 89% which obtained with CPAM. Also in case of using different bentonite in combination with flocculants, the highest percentage of GCC retained was 93% which obtained in case of using CPAM with Bt-PG. For RS, in case of using flocculants, the highest percentage of GCC retained was 74% which obtained with CPAM. Also in case of using different bentonite in combination with flocculants, the highest percentage of GCC retained was 83% which obtained in case of using CPAM with Bt-PG. As shown above the highest percent of GCC retained was obtained with HW in case of using CPAM with Bt-PG. This may be due to morphological character of HW. In addition, CPAM has high charge density and Bt-PG has high montmorillonite content and smallest diameter as well as high specific surface area. Thus without any flocculants or bentonite, GCC deposited on fibers but the bond strength is weak. With addition of flocculants GCC deposited with an increased in bond strength. In presence of flocculants and bentonite a strong bond is provided by bentonite particles. The optimum doses both flocculants (1 mg/g pulp) and bentonite (10 mg/g pulp) that obtained in the drainage results were used to study effect of their addition on physical properties (Optical and Mechanical) of handsheet made from different kinds of pulp. The results showed that physical properties were depending on the percent of GCC retained in handsheet. As shown previously, addition of flocculant and/or bentonite had a significant effect on increasing the percent of GCC retained in handsheets. As percent of GCC retained increased in handsheets the opacity were increased due to filler particles which filled the gaps between fibers mat. Brightness of paper was dependent on the Bt-type; it was increased in case of Bt-PG and decreased in case of using other types (Bt-ICMI, and Bt-OC) probably due to their iron content. Also basis weight and bulk density of paper sheets was increased as a result of increasing retention of GCC in paper sheets. But mechanical properties was decreased especially tensile strength and burst strength. This could be due to that GCC retained was sufficient to prevent the cellulosic hydroxyl groups from being bonded and also attributed to reduction in the bonded area as a result of trapping of filler, fibrils and fiber fines flocs between fiber areas which normally have hydrogen bonding.